Conventionally, as a deposition device that forms a thin film of an insulating substance on a surface of a semiconductor wafer (hereinafter, simply referred to as a ‘wafer’), for example, a chemical vapor deposition device (CVD device) has been used.
In the CVD device, a wafer is placed on a heated susceptor and a treatment gas is supplied into a treatment chamber to form a thin film of an insulating substrate on the wafer.
The insulating substance remains adhering to an inside wall of the treatment chamber and the susceptor after the thin film of the insulating substance is formed on the wafer. If the thin film formation on the wafer is carried out while the insulating substance adhering to the inside wall of the treatment chamber and the susceptor is being left as it is, the insulating substance is detached from the inside wall of the treatment chamber and the susceptor, which sometimes causes wafer contamination. In order to prevent such wafer contamination, cleaning for removing the insulating substance from the inside wall of the treatment chamber and the susceptor is necessary.
For cleaning, currently proposed is a method of removing the insulating substance through the use of a fluorine-based cleaning gas such as C1F3, NF3, or C2F6.
In this method, each material existing in the insulating substance, for example, lead zirconate titanate (Pb(Zr, Ti)O3: hereinafter, simply referred to as PZT) or barium strontium titanate ((Ba, Sr)TiO3: hereinafter, simply referred to as BST) is removed after being changed into fluoride.
However, fluoride of especially lead (Pb), zirconium (Zr), barium (Ba), or strontium (Sr) among these materials, is low in vapor pressure. Therefore, it is necessary to increase the temperature in the treatment chamber to as high as 600° C. or higher in order to remove the insulating substance containing these materials.
However, in order to maintain the temperature in the treatment chamber at the time of cleaning (cleaning temperature) at 600° C. or higher, it is necessary to use materials that are not softened at the cleaning temperature of 600° C. or higher for forming the inside wall of the treatment chamber, the susceptor, O-rings, and so on, which poses a problem of lack in realizability.
Even when the cleaning is conducted at 600° C., the use of the fluorine-based cleaning gas has a problem that the fluoride remains in the treatment chamber.